Refrigerant vapor compression systems are well known in the art and commonly used for cooling or heating air supplied to a climate controlled comfort zone within a residence, office building, hospital, school, restaurant or other facility. Conventionally, these systems have been used for conditioning air, that is cooling and dehumidifying air or heating air. These systems normally include a compressor, typically with an associated suction accumulator, a condenser, an expansion device, and an evaporator connected in refrigerant flow communication. The aforementioned basic refrigerant system components are interconnected by refrigerant lines in a closed refrigerant circuit and arranged in accord with known refrigerant vapor compression cycle schematics. An expansion device, commonly an expansion valve, is disposed in the refrigerant circuit upstream, with respect to refrigerant flow, of the evaporator and downstream of the condenser. In operation, a fan associated with an indoor heat exchanger draws air to be conditioned from a climate controlled environment, such as a house, office building, hospital, restaurant, or other structure, and passes that air, often mixed with an outside fresh air in various proportions, through that heat exchanger. As the air flows over the indoor heat exchanger, the air interacts, in heat exchange relationship, with refrigerant passing through that heat exchanger, typically, inside tubes or channels. As a result, in the cooling mode of operation, the air is cooled, and generally dehumidified. Conversely, in a heating mode of operation, the air is heated.
It is well known in the art that a refrigerant-to-water heat exchanger, rather than a refrigerant-to-air heat exchanger, may be used as the condenser for the purpose of heating water, rather than simply rejecting the excess heat to the environment. In such systems, the hot, pressurized refrigerant passes through the condenser coil in heat exchange relationship with water passing over the condenser coil, thereby heating the water. Water heating in conjunction with vapor compression cycle has been employed to heat water for homes, apartment buildings, schools, hospitals, restaurants, laundries, and other facilities, and at the same time provide conditioned air to those facilities. However, it will be necessary to upgrade the efficiency of conventional water heating refrigerant vapor compressions systems using conventional thermodynamic cycles and components to meet higher industry efficiency standards and government regulations.
Accordingly, it is desirable that a more efficient refrigerant vapor compression system is developed for heating water.